Speaking with a Birmingham accent is considered less intelligent or attractive than not opening your mouth at all, according to a university academic.

A study investigated how working-class applicants are being held down by a “class ceiling” when it comes to recruitment to top companies.

Professor Lance Workman, of the University of South Wales, carried out a series of tests after a report from the Social Mobility and Child Poverty Commission, which revealed evidence that recruiters favoured people with certain accents over others, regardless of academic merit.

The commission found the best paid jobs in the country were heavily dominated at entry level by people from more privileged socioeconomic backgrounds.

It discovered most people applying for jobs at elite firms had gone to Russell Group universities – and were more likely to be successful in their application than those who went to less selective universities.

Describing the discrimination as a wicked problem the commission recognised the scale of the complexity in turning it around and said political leaders needed to be “original, innovative and devious.”

Prof Workman said those who spoke ‘received pronunciation’ (RP) or ‘the Queen’s English’ had a better chance at being recruited because there was an implicit assumption that the posher the voice, the higher the IQ.

He said although RP was spoken by just three per cent of the population, it was recognised as the tongue of those belonging within the upper echelons of society.

He said: “In contrast, specific regional accents are often perceived as inferior and belonging to groups lacking in prestige.”

Prof Workman and a colleague decided to carry out research – randomly pairing accented voices with faces, and asked people to rate both how attractive and how intelligent a given young woman was when reading a passage with one of three accents – Birmingham, Yorkshire and RP.

He said: “We also added a silent condition where participants saw the face but did not hear any dialogue. We randomised faces with accents in order to control for differences between faces. The results suggested that, while regional accents do not have an effect on the perceived attractiveness of the speaker, they do have a significant effect on perceived level of intelligence.

“People ranked the Yorkshire accent as the most intelligent followed successively by RP, silence and then the Birmingham accent.

“The findings raise two questions. Why was the Yorkshire accent rated most highly? And why was the Birmingham one rated even lower than the silent condition?”

Prof Workman said the actual tone of the Brummie accent might be behind the stereotypes – and potentially harm candidates going fro top jobs from the city.

He said: “A number of studies have found negative associations with the Brummie accent. This may be related to the flat vowels that are associated with it.

“Examples of this include the pronunciation of pie as ‘poi’ and pint as ‘point’. A well known Birmingham joke involves the terms ‘cup of tea’ and ‘kipper tie’ being mixed up.

“Flattening of the vowels seems to be seen as an indication of low intelligence, despite not being supported by any empirical evidence. It is merely a negative stereotype.

“Despite changes in attitudes of the general populace to RP, when it comes to recruitment to the elite professions, it is clear that many of those with regional accents are still hitting a class ceiling.”